This invention relates to applying a liquid treatment composition to articles, and more particularly, to apparatus, methods and control systems that selectively apply treatment compositions, such as tints and the like, to articles, such as eyeglass lenses, by dipping the articles into liquid treatment baths containing the treatment compositions.
In the conventional manner of tinting eyeglass lenses, the lenses are maintained in a vat of hot tinting solution for a period of time until the lenses are tinted to a desired degree. Most of the equipment used today to tint lenses is simply modified food warming equipment. Instead of water, however, a fluid heat transfer medium, such as polyethylene glycol, is heated by heating elements located in the bottom of an outer tank. The heat transfer medium, in turn, heats a number, generally eight to twelve, and often nine, of one quart stainless steel steam table pans, pots or chambers contained in the outer tank. Dyes are typically dispersed in water. The water is heated to 200xc2x0 Fahrenheit, which is often the ideal temperature for tinting.
The heat transfer fluid heats all of the pans evenly. Because of this, it is difficult to heat one or more of the pans to a different temperature from other ones of the pans. If all of the pans are left uncovered, because of thermodynamic effects including water vapor loss, etc., the indirect heat provided to the pans by the heat transfer medium will be incapable of heating all of the pans to 200xc2x0 F., assuming the modified food warming equipment is powered using standard power lines at110 VAC, which produces a practical limit of about 1800 Watts.
With all of the pans covered, the maximum temperature of the heat transfer medium may reach above 212xc2x0 F., although the temperature will not rise significantly higher, since the pans will boil over. However, as soon as a lid is removed from a pan, the temperature will begin to drop. Also, when the lid is removed, the water level will usually tend to drop, and water will almost continuously have to be added. Restoring the water level will tend to further reduce the bath temperature.
Accordingly, despite the preferred temperature for dye baths of around 200xc2x0 F., the actual temperature of most conventional dye baths may generally be expected to be between about 150xc2x0 F. and 160xc2x0 F. This often causes distortion in the color of lenses tinted and also tends to unbalance the colors in the dyes. As a result, tinted lenses often require that their tinting be readjusted, a process which requires substantial time and artistic effort on the part of the person adjusting the coloring.
In order to provide tint gradients on lenses, the lenses are conventionally raised and lowered repeatedly, the lenses preferably being lowered a shorter distance as the dipping progresses, such that the lowest part of the dipped lenses contacts the treatment solution the most. As it is often desirable to have the darkest tinting at the top of the lenses, the lenses are typically held upside down as they are dipped into the treatment solution. The earliest gradients were formed on lenses by hand. Manually dipping the lenses up and down was the only practical way to form gradients by hand. The commercial machines used today still use this same up and down xe2x80x9cdippingxe2x80x9d motion approach.
The conventional steam table pans are cleaned by lifting them out of the tinter machine, dumping the contained water and dye, and cleaning the pan.
An example of conventional lens dyeing methods and apparatus that give a continuous colored density gradient is provided by U.S. Pat. No. 5,096,457 to Nakagawa et al. U.S. Pat. No. 5,453,100 to Sieloff discloses a method for color dyeing polycarbonate in which a graded tint is provided by slowly withdrawing the immersed polycarbonate material from a dye or pigment-containing mixture. A preparation of differential thickness coatings by dip coating, where the substrate is pivoted, is disclosed in U.S. Pat. No. 5,153,027 to Spagnoli.
An eyeglass tinting machine which utilizes a microprocessor-controlled stepping motor to control the vertical oscillations of a support structure is illustrated in U.S. Pat. No. 4,915,986 to Elias et al. In one mode, a gradient tint is achieved by lowering the top portions of the eyeglass lenses into a dye vat to the line at which the gradient starts, subsequent to which the machine will simultaneously reciprocate the lenses up and down and slowly withdraw them from the dye so that they are moving vertically at all times. An annular gradient optical lens tint system which may be used with the Elias et al. machine is disclosed in U.S. Pat. No. 4,201,955 to Chika et al.
U.S. Pat. No. 5,052,337 to Talcott et al. discloses a lens dyeing method and apparatus, including a heating element contacting a dyeing tank and a heat controller and sensor for dye solution temperature. The dye solution temperature is maintained and controlled within a preselected tolerance by a temperature controlling unit and its associated heater, which is connected to the dyeing tank. Talcott et al. also describes an automatic water fill apparatus associated with the dyeing tank to maintain the dye level without operator intervention. Additionally, the dyeing tank has associated with it a stirring device, preferably a magnetic stirrer. Talcott""s method uses a dye solution having an elevated boiling point to dye the lens material at temperatures above 212xc2x0 F. While Talcott et al. mentions the possible use of more tanks, the maximum possible to be heated at one time, due to power limitations, would be four tanks, assuming standard power lines, providing 110 VAC, is used.
A common limitation of the above-described devices and methods is the lack of an integrated and automated overall control system and apparatus for controlling and maintaining variables for different treatments including optimal temperatures, treatment duration, surface gradient treatments, etc.
This invention provides an apparatus, methods and control systems to dip treat articles in one or more of a plurality of liquid treatment bath chambers.
The apparatus includes one or more article raising and lowering devices and a plurality of treatment bath chambers. In one exemplary embodiment, each bath chamber has a separate heater, separate temperature and level monitors, separate filling and draining devices, and aerators to keep the treatment bath components in suspension.
One exemplary embodiment of the method includes treating articles, preferably eyeglass lenses, by supporting the articles on an arm and dipping them into one or more of a plurality of treatment bath chambers. In one exemplary embodiment, each treatment bath chamber separately contains assorted treating liquids such as tint coatings, UV protection coatings, scratch resistance coatings, neutralizing liquids for removing tinting, and rinsing liquids.
The control system can be provided with data identifying which bath chamber or bath chambers contain a particular type of treatment bath liquid. In one exemplary embodiment, the control system controls, for example, the temperature of each bath liquid, the liquid level in each bath chamber, the duration of treatment in each bath, and the speed of withdrawal from each bath to provide different gradient coatings on the articles. The control system can also generate an audible and/or visual signal of the end of the treatment duration in each bath. In another exemplary embodiment, the control system can also manage the power usage in the system, when necessary, by controlling which heaters receive power until all of the chambers are fully heated. Subsequently, the control system only provides power to heat those chambers whose temperatures have dropped to a predetermined temperature.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of embodiments.